A headlight, especially for motor vehicles, contains at least one optical system comprising a powerful light source and optical elements. The light source emits light rays and the optical elements represent a system of refractive and reflective surfaces, interfaces of optical environments and diaphragms that influence the direction of light rays within the creation of the output light trace.
In modern headlights of motor vehicles, multifunctional projector systems are commonly used, containing more mutually independent light units to create the low beam or high beam light trace. In the prior art, contributive light units are known that contribute to the creation of the output characteristic of the light trace by emitting light in specific zones in front of the driver on the carriageway. These contributive systems emit light together with the basic projection unit designed for the low beam or high beam light functions, increasing the intensity of light in front of the vehicle and at the same time ensuring a wide distribution of light in the space, achieving better lighting of the zones at the edges of the carriageway.
For design reasons, headlights of motor vehicles are often subject to the requirement that the light source and output lens be mounted deeper in the headlight bushing, which leads to the result that the distance between the output lens and the translucent cover of the headlight is large. If the light source and the output lens are recessed deep in the headlight bushing, the space between the output lens and the translucent cover of the headlight is restricted from the lateral sides by the lateral walls of the covering mask or bushing, which create a side trimming of the light beam with their bevelled edges, which is manifested on the carriageway surface as a visible boundary between the area that is intensively lit by direct light rays and the area where the headlight does not light due to the trimming of the light beam. A visible boundary of the area illuminated by direct light rays is a disturbing element for drivers.
The disadvantages of deep recessing of the light source and output lens in the headlight bushing are mainly manifested with additional contributive systems whose task is to provide supplementary light functions to increase the total light output of the headlight. The additional contributive systems are usually arranged in the headlight bushing in one unit together with the basic projection unit or separately. They generally use planar LED light sources whose light beam gets wider in the direction towards the output lens at the same rate in the vertical direction as in the horizontal direction and is therefore significantly trimmed by the lateral bevelled edges of the bushing or the covering mask at the lateral sides.
It is true that the light pattern can be adapted or shifted in the horizontal direction to avoid creation of a visible boundary between the intensively lit area and the unlit are, but the task of the output lens is to direct light rays in the vertical direction. A combination of tasks in the horizontal and vertical direction in one output lens is difficult or nearly impracticable.
A combined lamp for motor vehicles is known from the document EP1033527 that comprises, besides a central reflector, lateral edge reflective surfaces of a concave shape, continuing the central reflector. Light rays reflected from the lateral edge reflective surfaces produce a concentrated light beam on the display surface of the carriageway that supplements the light pattern emitted by the central reflector. The light beam emitted by the lateral edge surface generally flows around the output lens. In the transversal direction to the optical axis of the headlight the lateral edge surfaces significantly exceed the edge of the output lens, increasing the total diameter of the headlight, which is undesired. Conversely, a headlight is desirable that has a smaller outer diameter enabling easier integration in the car body and adaptation of the car body design.
The document EP1970619 discloses a projection unit of a motor vehicle that comprises the basic optical elements for emitting the basic light beam on the one hand and secondary optical elements for emitting a secondary, supplementary light beam on the other hand. The secondary optical elements collaborate with secondary elements for collection of light rays or secondary elements for reflection or dispersion, designed to deflect a major part of the light emitted by the secondary light source to the direction of the basic projection optical system, and to create an additional pattern on the display surface of the carriageway. According to one of the variant embodiments, reflective surfaces surrounding the light beam emitted by the light source are assigned to the secondary LED light sources to direct the light beam to the output lens. The reflective surfaces may consist of multiple parts. The light beam may be directed on the horizontal plane, or it may be directed to a plane inclined with respect to the horizontal plane. The reflective surfaces are arranged next to the light source to capture and direct light rays that are not emitted from the light source directly, but propagate laterally in the vicinity of the planar LED light source. Since the reflective surfaces are arranged at the lateral sides of the LED light source and have a three-dimensional shape of the shell of a rounded body, they significantly exceed the edges of the light source on the transversal plane and increase the transversal cross-section of the projector. With their position and their three-dimensional shape, the reflective surfaces do not eliminate the undesired boundary between the area that is intensively lit by direct light rays and the area that is not lit by the headlight due to the light beam being trimmed by the outer lateral bevelled edges of the bushing.
The document DE19860669 discloses a projection unit of a motor vehicle with a light source, with the basic reflector for reflection of light from the light source to a convergent light beam, with an output lens and with a diaphragm arranged essentially below the optical axis to create the upper boundary of the light and darkness. In the projection unit, between the basic reflector and the output lens, another diaphragm is arranged to blind at least a part of the light that would otherwise illuminate the central area on the carriageway near the vehicle, and an additional reflector is provided to reflect and guide an additional light beam in a direction outside the output lens and to boost the lighting of the area on the carriageway near the vehicle. The reduction of the luminous intensity in the area on the carriageway near the vehicle reduces the sharpness of the transition between the lit area on the carriageway near the vehicle and the surrounding area, which is not lit by the light of the additional reflector. The additional reflector is arranged in the perimeter area of the basic reflector, bound to its front edge. The arrangement of the additional reflector increases the transversal dimensions of the basic reflector, which is not desirable. The reduction of the sharpness of the transition between the lit area on the carriageway near the vehicle and the surrounding unlit area is achieved at the expense of the total luminous intensity, which is generally undesirable.
The document WO2012109681 discloses a LED light module for lamps of motor vehicles comprising a LED light source and an output lens, and arranged between them, a light tunnel for the passage of light emitted by the LED light source. Having passed through the light tunnel and the output lens, the light of the LED light source creates an additional (contributive) light pattern on the carriageway in front of the vehicle. During the passage through the light tunnel, which has the required length, the light from the LED light source is mixed and formed in such a way that the required distribution of light is achieved. The light tunnel is created in a carrier plate made of a transparent material, and to achieve the required length of the light tunnel, a solid projection is created in its place on the carrier plate which the light tunnel passes through. The walls of the light tunnel are partly or completely fitted with a reflective surface to reflect light rays. The carrier plate is made of two parts whose dividing plane passes through the light tunnel or one of its walls. On the transparent carrier plate, more, secondary LED light sources are arranged, whose light is diffused in the transparent carrier plate, which makes the carrier plate very massive and expensive to manufacture. The carrier plate is produced with the use of injection moulding and the size of the walls of the light tunnel is limited in the light propagation direction and is insufficient for guiding of light rays. A disadvantage of this technical design is that the shape of the light tunnel cannot be flexibly adapted to the mechanical design of the headlight.
The goal of the present invention is to eliminate the above-mentioned shortcomings of the prior art, namely to eliminate the visible boundary created by the bevelled edges of the walls of the bushing or covering mask on the carriageway surface between the area that is intensively lit by direct light rays and the area where the headlight does not light due to the trimming of the light beam, and at the same time to increase the total illumination intensity of the carriageway in front of the vehicle while the shape of individual components of the contribution system can be variably adapted to the mechanical design of the entire headlight.